Charge support for the bases of cover-type annealing furnaces



E. D. SPANGLER 2,481,170 CHARGE SUPPORT FOR THE BASES OF COVER-TYPE ANNEALING FURNACES 2 Sheets-Sheet 1 9% R 9b d b p l5M9- E D. SPANGLER 2,481,170

CHARGE SIZIPPORT FOR THE BASES 0F COVER IYPE ANNEALING FURNACES Filed Feb. 25, 1948 2 Sheets-Sheet 2 lwenlar: 42A 0 j m/612 5E,

Patented Sept. 6, 1949 CHARGE SUPPORT FOR THE BASES OF 7 COVER-TYPE ANNEALING FURNACES Earl D. Spangler, Gary, Ind., assignor to. Carnegie-Illinois Steel Corporation,

of New Jersey a corporation Application February 25, 1948, Serial No. 10,808 9 Claims. (Cl. 26349) This invention relates to apparatus for annealing sheet metal and, in particular, to a charge support for the base of a cover-type annealing furnace.

The annealing of sheet metal, either a piled sheets or coiled strip, is now generally carried on by the aid of cover-type furnaces. In the processing of sheets, they are piled on a support resting on the furnace base with which the cover cooperates. This practice involves certain diificulties. The support, usually a heavy steel plate; does not remain flat but is subject to buckling or warping after repeated heating and cooling in accordance with the required annealing cycle. This is the result of the expansion andcontraction of the support as well as the charge or pile of sheets thereon. Any departure of the support from the flat condition is, of course, transferred to the sheets under the heavy load imposed by their weight, and the softening of the metal at annealing temperature. Lack of flatness in the annealed sheets seriously impairs their quality. This difiiculty is aggravated by the fact that practically all sheet metal is now reduced to gauge by cold-rolling and the highly cold-worked condition of the material prior to annealing increases its susceptibility to loss of flatness as by buckling, on heating to annealin temperature. The coldrolled sheets as delivered to the annealing department, furthermore, are not always flat but may exhibit a degree of waviness or undulations.

The lack of substantial flatness in the base plate or the presence of waviness in the sheets being annealed causes a further difficulty, i. e., the sticking together of adjacent sheets as a result of the heat and pressur existing under annealing conditions. Any high spot on the base or in any sheet, of course, concentrates the pressure of the weight of the sheets thereabove and is likely to cause sticking of the sheets lower down. Because of this difiiculty, it has been necessary heretofore to limit the height of the piles of sheets placed on an annealing base so as to avoid the heavy loads on the lower sheets which are conducive to sticking. For this reason, it has not been possible to obtain the maximum production for which the furnaces are designed.

A still further difficulty always present in annealing sheets in piles is that the top of the pile has a greater area subject to direct heating than the bottom with the result that there is usually a substantial difierence between the temperatures of the sheets at the top and bottom, respegtiyely,

2 as the charge comes up to temperature. This may give rise to objectionable differences in the physical characteristics of annealed sheets from different portions of the pile.

It is the object of my invention to provide a charge support which overcomes the aforementioned objections. In a preferred embodiment, the base of my invention includes a bottom floor or deck with a refractory hearth laid thereon. A metal base plate disposed on the hearth has a plurality of beams upstanding thereon in spaced parallel relation. The beams preferably have an enlargement in the form of a head or ball at the bottom and a flange or flanges at the top with a connecting web therebetween. The ball or head of each beam is welded to the plate and the beam flanges'together constitute a grating adapted to receive the charge to be annealed. If sheets constitute the charge, they are piled directly on the beam flanges. The beams maybe lengths of track or T-rail disposed with the head down. The base plate is preferably sectionalized, particularly for large furnaces. That is to say, I employ a plurality of separate pieces of plate disposed side-by-side on the hearth, each having beams welded thereto, instead of a unitary integral base plate.

The head of a track rail is rounded at the corners and slightly on top. The beams forming the grating of my improved support are adapted, therefore, to rock transversely to a limited extent, thus accommodating any difference between the expansion and contraction of the piled sheets and of the base plate itself. I preferably weld the rail heads to the base plate in a special manner to avoid interfering with this rocking movement. The latter also gives the base plate itself a limited freedom for expansion and contraction independent of the charge.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanyin drawings illustrating the preferred embodiment. In the drawings,

Figure 1 is a plan view of a furnace base having the charge support of my invention thereon;

Figure 2is a longitudinal section taken alone the plane of line IIII of Figure l;

Figure 3 is a transverse section taken along the plane of line IIIIII of Figure 1; and

Figure 4 is a fragmentary plan view showing one corner of the improved charge support with parts broken away for clearer illustration.

Referring in detail to the drawings, a furnace base, indicated generally at B, comprises a bottom it, a refractory hearth ll laid thereon and a charge support, indicated generally at S, resting on the hearth. The bottom it includes a grid of longitudinal and transverse structural members l2 and it having a floor plate It thereon and adapted to be placed on a suitable foundation, such as a slab or pier of concrete. A sealing channel I5 for an inner cover extends around the hearth Ii being composed of refractory brick. A sealing channel it extending around the edge of the bottom outside of the channel i5 is adapted to receive the sealing flange depending from a heating cover disposable over the inner cover.

The charge support S comprises a metal base plate i1 having beams l8 extending transversely thereof in spaced parallel relation. The plate I! is composed of four sections, being divided along median longitudinal and transverse lines. The edges of the several sections are disposed in abutting relation, as shown in Figure l. The beams ill on opposite sides of the longitudinal median line are in alignment with their innerends spaced slightly apart, as indicated at l8.

' The beams l8 may conveniently be lengths of track or T-rail disposed head down on the plate ii.

The lengths are positioned on centers so spaced that the edges of the flanges 20 of adjacent beams will be spaced apart. The flanges of 'the beams together constitute a raised deck in the form of a grating on which a pile of sheets to be annealed, indicated at 2i, may be directly loaded. When the pile has been placed on the support 8, the spaces 22 between the webs of adjacent beams constitute transverse passages beneath the pile through which the atmosphere within the inner cover may circulate, in direct contact with spaced portions of the bottom of the pile for heating the latter by convection. The flanges of adjacent beams are cut back for a portion of their length at intervals along their base, as indicated at 23, to provide slots for lifting hooks used to place the sections of the charge support in position on the base by the aid of a crane.

The head or ball of the section of an ordinary track rail is rounded at the corners and is slightly convex on top. Thus the beams20 are adapted to have a slight transverse rocking movement to accommodate differential expansion and contraction between the pile of sheets 2i and the sections of the base plate ii. The beams are welded to the plate in a special manner, shown in Figure 4, to avoid interference with this movement. Intermittent line welds 24 of limited length, staggered on opposite sides of the beams, are formed between the heads of the lengths of rail and the base-plate sections. These welds are spaced along the entire length of the beams.

Supporting bars 25 for holding thermocouples adjacent the bottom of the charge are welded to the flanges of adjacent beams l8 at spaced points along the length of the support.

In operation, as the charge is gradually heated, it has limited freedom for expansion in length as a result of transverse rocking of the beams, even though the base plate heats up at a lower rate and its expansion accordingly lags behind that of the charge, When differential expansion or contraction occurs, the beams are each capable of making individual adjustments to compensate for any movement of the portion of the charge which they support, or the plate which supports them, all of which may be considered normal conditions imposed by the heating and cooling cycle of tempertures. During any or all of the relative movements aforesaid, the upwardly exposed beam flanges maintain a flat, continuous surface-tosurface contact with the charge because of their capacity for self-readjustment just explained.

The charg support of my invention has been shown by the results of actual operations to be characterized by important advantages. In the first place, it does not exhibit departures from flatness, such as those characterizing charge supports used previously, even after repeated annealing cycles. In other words, the original flatness of the support is not destroyed by the expansion and contraction of the support itself or the charge of material disposed thereon. This appears to result from the slight transverse rocking movement of the beams which is permitted, as above explained, to allow for any difference in the rate of expansion or contraction of the charge, as compared to that of the base plate. The plate itself is, therefore, less likely to buckle after repeated expansion and contraction since it has limited freedom to move independently of the charge on the flanges of the beams.

My improved charge support makes it possible to anneal a charge of the full height for which the inner cover and heating cover of the furnace are designed without the occurrence of stickers." An increase of 30% in the tonnage of sheets annealed per base per hour has been achieved as a result. This result flows directly from the avoidance of the loss of flatness characteristic of previously known supports. The spaced beams supporting the charge above the base plate proper serve to relieve stresses which would otherwise be occasioned by differential expansion and contraction between the charge and plate, and obviate regions of pressure concentration caused by the condition of waviness in the sheets when piled on known supports. The beams also provide a suport of extrem rigidity preventing deflection as a result of expansion of the charge and thus tending to cause expansion to occur in the hori- Zontal plane only.

The sectional construction of the support distributes the total expansion and contraction between the several sections since the latter are free to expand and contract independently. It will be understood, however, that the sectional construction is optional and would probably not be employed in the case of bases of smaller sizes.

The improved support also permits convection heating of the bottom of the pile by circulation of atmosphere gases through passages 22, thus tending to reduce the temperature diflerential between the top and bottom. This results in the production of an annealed product more nearly uniform in physical characteristics, regardless of the position in the pile occupied by a particular sheet.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the details of construction may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A charge support for a furnace base including a bottom and a hearth thereon adapted to accommodate a cover enclosing a charge on the base, said support comprising a metal base plate on said hearth and a plurality of beams secured to said plate in spaced parallel relation forming a grating, said beams each having a flange at the top and a head at the bottom narrower than the flange, the head being welded to the plate at intervals along the length of the spaced relation, said beams a t top provl a grating adapted t charge, and heads at the bottem M the flanges welded to the plate whereby a limited trverse o flanges is permitted.

t. h charge support tor the base of a serene furnace comprising a metal base plate d a pl rallty oi track rails secured rein in spaced relation, said rails their hanzrm the top provi adspd to i-ve a charge and. their heads posed downwar secured to the plate, whereby l" movement of the :1 1 is w WM 5. The apparatus deed by 1 v terized by said beams "11 secured to the plate by intermittent lines of welding measured on opposite sides of the r.

6. In a furnace base including a bottom and a hearth thereon, the improvement com a. charge support composed oi a base plate resting on the hearth and a plurality of beams extending transversely oi the plate in spaced relation, said having flanges at the top thereof providing a m adapted to receive 3 6 charge and heads at the bottom thereof secured to the plate at points spaced therealong so as to permit limited movement of the flanges transversely of their length.

7. The apparatus defined by claim 6 characterized by said beams being lengths of T-raii disposed head down.

8. The apparatus defined by claim 6 characterized by said beams being secured to the plate by intermittent lines 01' welding staggered on opposite sides of the rails.

9. A charge support for the base of a covertype furnace comprising a metal plate adapted to rest on the base and a plurality of lengths of T rail welded head down to said plate in parallel spaced relation, the flanges oi said lengths lying substantially in a common plane and providing a grating adapted to receive a charge.

EARL D. SP6

RENCES CITED The following references are of record in the file of this patent:

STATES PA'I'ENTS Number Name Date 726,338 Patterson Apr. 28, 1903 728,578 Huxley May 19, 1903 1,037,665 Rockwell Sept. 3, 1912 2,081,990 ein June 1. 1937 FOREIGN PATENTS Number (iountry Date 452,204 Great Britain A118. 18, 1938 

